Yes it's correct to a certain point. Viewing distance is the deciding factor, not necessarily the resolution. 720p on a 720p panel will look better than 720p on a 1080 panel. However, you can't get hold of a 720p panel because 1080 is the norm. While higher resolutions are "better", by the time OLED become more affordable, everybody that is looking for the best picture quality, will immediatly buy a 1080 OLED instead of say a 2.5k or a 4k monitor. There is a chart online you can use, it's the THX chart that holds true for everybody with 20/20 vision acuity, with a min and max recommended viewing distance at various resolutions. But 1080 is already high enough to not see any pixels from a normal viewing distance which is typically 2-3 feet on a normal mid sized monitor. A lot of people confuse pixels for pixel structure too, which turns this topic into a heated debate because suddenly everybody is an "expert". Another issue with this is that while watching a YouTube video, which is highly compressed, you will see different types of artifacts. This is not caused by the "low" resolution (word used to market higher displays than 1080). You will guranteed see no "pixels" from a normal viewing distance if the source is uncompressed 1080 (or 720). There are so many different opinions on this topic, and people are more sensitive to this than others, but from a technical standpoint. If everything is right (same panel, just different resolution), then no--you wouldn't be able to tell the difference if you have an untrained eye.
Note: By uncompressed I'm talking about blu-ray, or similar. Gaming on higher resolutions is fantastic, however this is an issue for video, not games. You can force your GPU to render at a much higher resolution and then downsample it to your native resolution, which will make the game look great. Because this technique exist, a higher resolution monitor shouldn't be your main concern if you're playing games, because in-game settings matter so much more than resolution ever will.